Mosquito genes suggest climate flexibility

U. OREGON (US) — Using cutting-edge genetic tools, scientists have shown that temperate and polar animal species may be much more resilient to rapid climate change than previously expected.

Thousands of species in temperate zones use the length of day—or photoperiodism—to trigger irrevocable life and death behaviors, including the timing of development in the spring, when to enter dormancy in the fall, when to reproduce, and when to migrate.

Biologists in the University of Oregon lab of William E. Bradshaw and Christina Holzapfel studied ancient and derived populations of the pitcher-plant mosquito, Wyeomyia smithii, which completes its pre-adult development in the water-filled leaves of the purple pitcher plant.

The researchers created three forms of genetic maps of mosquitoes from New Jersey, northern Maine, and southern Alabama.

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They found that the underlying genetic architecture of photoperiodism is highly variable, not only through evolutionary time but also within populations. Species have a high level of built-in genetic flexibility with which to respond to the seasonal demands of a changing world, a fact that co-author Holzapfel says “will provide more challenges than previously expected in efforts to control unwanted pests and invasive species in temperate climates.”

Bradshaw and Holzapfel had shown earlier that an interpretation of length of day by animals is coded in the genes and can be shifted in as few as five years in response to climate change.

Their ongoing project seeks the basis for the evolution of seasonal timing at the level of genes and an understanding of how the integration of genes has changed over geographical ranges and over different evolutionary time scales.

Bradshaw, the lead author in the new study, says that “gaining such genetic knowledge is key to predicting and mitigating the movement of vector-borne diseases from tropical to temperate zones of Earth as vectors and their hosts migrate into increasingly milder northern climates.”

The National Science Foundation, under the American Recovery and Reinvestment Act, and a subsequent grant provided the major support for the project. The National Institutes of Health, W.M. Keck Foundation, and the M.J. Murdock Charitable Trust provided additional funding.